




Engineer School 
XL S. Rxmv 

...» F 9 82. 



THE 



COMBUSTION OF FUEL, 



WITH SPECIAL REFERENCE TO 



SMOKE PREVENTION 



LIBRARY. 
ENGINEER SCHOOL, 

WASHINGTON BARRACKS, D. C. 

R9C , d FEBRUARY. Z/Q 0< ? 
Professor W. W. F. PULLEN 



M 



Wh.Sc. A.M.I.C.E., M.I.M.E. 



Price, 3s. 6d. net. 



THE SCIENTIFIC PUBLISHING COMPANY, 
MANCHESTER. 

(All Rights Reserved.) 

D. VAN NOSTRAND COMPANY, 

NEW YORK. 






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PEBFACB 



Much of the substance of the following pages was given 
in a lecture to the Association of Sanitary Inspectors, at 
the Carpenters' Hall, London, on March 4th, 1899. It 
was reproduced in The Mechanical Engineer immediately 
afterwards, with considerable additional matter. The 
whole has been collected, and is now presented complete 
for the first time. 

In a lecture it is impossible to attempt to describe all 
the different appliances for the promotion of combustion, 
so that there are many machines and other apparatus not 
mentioned. Those which were originally given are 
typical examples of existing practice. 

W. W. F. PULLEN. 




THE COMBUSTION OF FUEL. 



WITH SPECIAL REFERENCE TO SMOKE PREVENTION. 



Coal, of one quality or another, is almost the only fuel 
used for manufacturing purposes in this country, and it is 
principally with its application to the raising of steam for 
motive power and heating purposes in steam boilers that I 
propose to deal in this lecture. 

It may be advantageous to first glance at the different 
kinds of coal which may be used in a boiler furnace. 

Varieties of Coal. — By far the most extensively used 
are the bituminous coals, so called because they evolve 
gas on heating, which burns with a smoky, yellow flame, 
like bitumen. These coals differ considerably in properties, 
and are very generally used for steam production. They 
are also the coals which give most trouble in the way of 
smoke. 

Anthracite is a very hard coal, containing but little 
volatile matter, and consequently burning with little or no 
flame. It produces next to no smoke. 

Smokeless steam coals are those which, if not pure 
anthracite, approach it very nearly in character, while 
they burn with short flame and little smoke. 

Cannel coal is used almost entirely for gas making on 
account of the large amount of volatile hydrocarbon it 
contains. Lignite is a comparatively young coal, and, as a 
rule, much inferior to those mentioned above. 

Slack, dross, and smudge are names given to very 
inferior fuel, which can only be burnt economically with 
the aid of a good draught. 



CLASSIFICATION AND ANALYSES OF COALS. 

Professor Humboldt Sexton has classified coals in the 
following manner : — * 



Kind of Coal. 


Carbon 
per cent. 


Hydrogen 
per cent. 


Oxygen 
per cent. 


Non-caking Coal, Long Flame... 


75 to 80 


5-5 to 4'5 


19-5 to 15 


Gas Coal 


80 to 85 


5-8 to 5 


14-2 to 10 






Furnace Coal 


85 to 89 


5 *5 to 5 


11 to 5-3 






Coking Coal 


88 to 91 


5-5 to 4-5 


6 to 5-3 






Anthracite Coal 


90 to 93 


4-5 to 4 


5-5 to 3 







The analyses of a few different kinds of coal are given 
below : — -f- 





Wajne's 

Merthyr 

Steam 

Coal. 


Tupton 
Slack. 


Anthra- 
cite. 


Bitu- 
minous. 


Carbon 


87-49 
3*66 
2-69 
1-17 
•79 
3-00 
1-20 

15000 


70-04 
5-16 

1 9'42 

11-86 

3-52 

13400 


91 5 
3-5 

2-6 

2-4 

15250 


87 


Hydrogen 

Oxygen , 


5 


Nitrogen 

Sulphur 


4 


Ash 


4 


Moisture 




Calorific value in B .T . U. 


15400 



Combustion. — The phenomenon of combustion may be 
described as the evolution of heat, due to rapid chemical 
combination, and is only complete when every constituent 

* Fowler's " Mechanical Engineer's Pocket Book," p. 251, 1899 
edition. 

t These are analyses of samples which are fairly typical of different 
coals used in boiler furnaces. 



AIR REQUIRED FOR COMBUSTION. 7 

of the fuel which is capable of combining with oxygen has 
taken up the maximum amount of that gas ; or, in other 
words, has reached its highest state of oxidation. Thus, in 
any sample of coal the carbon must be burnt to carbon- 
dioxide (C0 2 ), the hydrogen to water (H 2 0), and the sulphur 
to sulphur-dioxide (S0 2 ). 

If the carbon had left the flue as carbon-monoxide (CO), 
combustion would be said to be incomplete, and a consider- 
able waste of heat would be the result ; because the carbon- 
monoxide may combine Avith further oxygen, and give out 
further heat in forming carbon-dioxide (C0 2 ). 

The number of British thermal units (B.T.U.) evolved 
by the combustion of 1 lb. of each of the different con- 
stituents of coal are given below : — 

1 lb. hydrogen burnt to H 2 

(steam) 53,340 B.T.U. 

1 lb. carbon burnt to C0 2 14,540 „ 

1 lb. carbon burnt to CO 4,350 

1 lb. carbon-monoxide burnt to 

C0 2 4,370 „ 

1 lb. carbon in the form of CO 

burnt to C0 2 10,190 „ 

1 lb. sulphur burnt to S0 2 4,000 

When the reverse action takes place, heat is absorbed 
instead of given out by the constituents of the fuel ; for 
example, if water is broken up into its constituents 
hydrogen and oxygen, then an amount of water (9 lb.) 
containing 1 lb. of hydrogen would have to receive 61,260 
British thermal units before complete dissociation could 
take place. 

The composition of atmospheric air is approximately : 

By weight 23 per cent oxygen and 77 per cent nitrogen ; 
By volume 21 per cent oxygeu and 79 per cent nitrogen ; 

and consequently, at least, 11*5 lb. of air will be required 
to supply 2 '6 5 lb. of oxygen to burn 1 lb. carbon ; and at 
least 34*6 lb. of air will be required to supply 7*97 lb. of 
oxygen to burn 1 lb. of hydrogen. Roughly speaking, each 
pound of carbon requires at least 142 cubic feet of air, and 
every pound of hydrogen requires 430 cubic feet of air for 
combustion. 

For this combustion to be perfect each molecule of com- 
bustible matter must come into contact with corresponding 



8 AIE REQUIRED FOE COMBUSTION. 

molecules of oxygen, and consequently the air supplied must 
be very intimately mixed up with the combustible matter 
while it is at a temperature at which chemical combination 
can take place. 

In this lies the secret of the economical burning of fuel 
and the prevention of smoke. 

To permit of the intimate contact of the constituents of 
the fuel with the oxygen of the air much more of the latter 
must be supplied than the figures above indicate, because 
it is no easy matter to bring about these suitable condi- 
tions for combustion. 

It must be evident at the outset that there is much 
greater probability of a thorough mixture when the air is 
admitted to the fuel in a large number of small jets than 
by a few large jets. 

It must also be evident that the less excess of air sup- 
plied the higher will be the temperature of combustion, 
and the smaller the quantity of heat carried away up the 
chimney and wasted. 

We now see the kind of problem which the engineer 
has to solve in the economical combustion of coal. An 
excess of air is absolutely necessary, but that excess must 
not be greater than that required to produce complete 
combustion. 



30 



20 



d 10 



: , l.j..;s!:!*' : 

llllllllllllllllHJttfHI^ 



20 40 60 80 

Excess of Air Per Cent. 

Fig. 1. 



100 



120 



Some idea of the loss of heat through excess of air 
may be gathered from the accompanying diagram (Fig. 1). 



THE ECONOMETER. 9 

The quantities along the base represent the percentage 
excess of air, and vertically are plotted the corresponding 
losses of heat per cent. The gases are here assumed to 
pass into the chimney at about 600 deg. Fah. 

An excess of air dilutes the chimney gases and makes 
the percentage of carbon-dioxide (C0 2 ) less than would 
be the case if there were less air. Hence, conversely, an 
increase of C0 2 indicates a decrease in the excess of air 
if combustion is complete. 

An analysis of the flue gases at once indicates the 
excess of air by the amount of free oxygen which they 
contain. Also, a knowledge of the C0 2 will give a toler- 
ably accurate value of the excess of air if combustion 
has been complete. 

The Econometer. — An instrument which indicates con- 
tinuously the percentage of C0 2 in the chimney gases is 
supplied in this country by Messrs. Meldrum, of Man- 
chester, and is shown in the next illustration. It is 
called the " Econometer," because the percentage of C0 2 
which it measures also indicates the relative economy of 
the furnace. 

The relative density of some of the constituents of 
furnace gases may be obtained from any book of tables. 
They will be found to be : — 

Carbon-dioxide (C0 2 ) '00198 

Carbon-monoxide (CO) -00126 

Oxygen '00144 

Sulphur-dioxide (S0 2 ) '00288 

Nitrogen '00126 

It will be noticed that of all these sulphur-dioxide is 
the heaviest, but as there is always only a very small 
quantity its influence in comparison with the large 
quantity of carbon-dioxide will be almost inappreciable. If 
there is in the products of combustion a relatively large 
quantity of C0 2 , we conclude that the combustion has 
been complete without a great excess of air ; but should 
the quantity of C0 2 be small, then the excess of air has 
been very much greater than is necessary, and, conse- 
quently, much heat has been carried up the chimney 
thereby. If, on the other hand, there appears in the 
chimney gases more than a trace of carbon-monoxide, com- 
bustion has not been complete, and heat has been wasted 



10 



THE ECONOMETER. 



through imperfect combustion. In modern boiler furnaces 
not more than a trace of CO should be produced. 

_ The difference in density of the constituents of the 
chimney gases is made use of in the econometer. Pre- 
ferring to the illustration, a chemical balance is situated in a 




^ 



case with a transparent front which is bolted to the wall. To 
the left arm of the balance is suspended an inverted glass 
vessel 20, into the interior of which the fixed pipe 19 
is placed. This pipe is connected to the flue, and through 
it are aspirated the chimney gases. If the balance pointer 
indicates zero when the inverted weighing globe is full of 



THE ECONOMETER. 11 

air, then the introduction of a heavier gas, such as C0 2 , 
would cause the left end of the balance arm to move 
downwards ; and if the balance is very stable — that is, if its 
of centre of gravity is, comparatively speaking, far below the 
suspending knife edge — the amount of depression of the 
left arm, and consequently the movement of the pointer, 
will indicate the amount of increase of weight in the 
weighing globe. This is the principle of action of the 
econometer. 

A connection is made with the flue at 61, through 
which the gases are taken to the wood wool filter 56, from 
which it passes to the cotton wool filter 51. They are then 
passed through the calcium chloride tube, in which all 
moisture is extracted, after which the gases are taken 
direct to the weighing globe by the tubes 23 and 19. To 
produce a Continuous circulation of gases through the 
instrument the lower end of the weighing globe dips into 
the vessel 21, which is connected by the pipes 22, 62, and 
68, to the chimney or main flue, and which acts as an 
aspirator. 

This instrument gives a continuous record of the state 
of combustion by registering the percentage of C0 2 in the 
furnace gases, and that the record is accurate enough is 
shown by the following comparisons, which are taken from 
a number. The percentage of C0 2 was also determined 
simultaneously by an Orsatt apparatus. In each case the 
figures given are the average values of a large number of 
determinations : — 



C0 2 by Econometer I 16*84 

C0 2 by Orsatt apparatus ... | 16*83 



15*56 
14-92 



16*27 
16-38 



If there were no excess of air and the combustion 
complete, there would be a little over 20 per cent of C0 2 
by volume in the products of combustion. Fifteen per 
cent of CO 2 is considered very good, but from 14 to 11 per 
cent is more common, while 6 and 7 per cent is not un- 
known. Leakage of air through the brickwork of the flues 
often occurs, and this materially reduces the percentage of 
C0 2 as well as the efficiency of the boiler. This can be 
detected with the econometer b}^ connecting the instrument 
to a point in the flue as near the fire as convenient, and at 
the same time with the chimney. An observation is taken 
with one connection, and after switching over to the other 
connection another observation is taken. The difference 



12 COMBUSTION OF FUEL. 

in the readings of the econometer is chiefly cine to the air 
leakage. The leakage of air into the fines is the chief 
cause of error in the econometer when there is any, and 
the supplementary connection is sometimes awkward to 
provide in an existing boiler setting. 

Although complete combustion is much to be desired 
in populous districts, it does not necessarily produce maxi- 
mum economy nnder all conditions. As an instance of 
what I mean, let ns take the two methods of burning coal 
gas. With the Bunsen burner we obtain a thorough 
mixture of air with the gas before combustion takes place, 
and the result is a non-luminous flame. With the fishtail 
or batswing burner there is no previous mixture of air 
with the gas, and some of the carbon becomes separated 
in the flame and rendered incandescent, producing a 
luminous flame. The latter is a good radiator, while 
the Bimsen flame is a bad radiator. As a great 
quantity of the heat generated in a boiler furnace reaches 
the furnace plates by radiation, it is evident that flame in 
a furnace is very desirable, and is absolutely necessary 
unless the amount of heating surface is very large, and 
so disposed that the furnace gases can be made to give 
up their heat by contact. 

The analogue of the Bunsen flame is not found 
in the boiler furnace, as the air for supporting combustion 
does not mix with the gaseous part of the fuel, prior to 
its introduction to the furnace, as in the Bunsen burner. 
What actually happens more nearly approximates to the 
chain of events in the batswing burner, where a luminous 
flame is produced. 

When green coal is first placed upon the fire, the 
volatile part of it, consisting of hydrocarbons, is very 
quickly distilled off, leaving behind the non-volatile 
portion called coke. These hydrocarbons burn with a good 
deal of flame, and the major portion of the heat thus pro- 
duced finds its way to the furnace plates by radiation. 
The heat of combustion of the residue is given to the water 
partly by radiation from the incandescent coke and partly 
from the contact of the hot gases with the heating surfaces. 

If the hydrocarbons before igniting are thoroughly 
mixed with air at a sufficiently high temperature, complete 
combustion will take place without smoke. But should 
the supply of air be insufficient, or the air not thoroughly 
mixed with the hydrocarbons, partial combustion will take 
place, and some of the carbon will be condensed by the 



METHODS OF FIKING. 13 

breaking up of the hydrocarbons. The carbon is separated 
in the form of lamp black, or soot, and in the finely-divided 
state as found in the chimney varies in appearance from a 
faint grey to the densest black, depending much on the 
relative quantity. 

Most authorities agree that, when once formed, soot 
burns with great difficulty even in contact with air at a 
high temperature ; hence it is very necessary to prevent 
its formation rather than attempt to do awa} r with it after 
it is formed. 

I mentioned just now that complete combustion may 
not under certain circumstances be the most economical. 
For instance, a large excess of air may produce complete 
combustion without smoke, but with the result that an 
enormous amount of heat was being wasted in heating the 
excess of air and sending it up the chimney. On the other 
hand, a very slight amount of smoke indicates that com- 
bustion is not quite complete, but at the same time it also 
indicates that the excess of air is probably small, and con- 
sequently the waste on that account is not large. This is 
why some owners of works prefer a slightly smoky 
chimney. 

Methods of Firing. — It has been shown by experience 
that very careful hand-firing with most kinds of coal will 
prevent smoke if the fires are not forced too hard, but 
where one careful fireman can be found there are many who 
cannot be placed in the same category. 

The best method of firing is believed to be that called 
the " alternate method," where one side of the fire is fed 
at a time, so that the volatile gases given off by the green 
coal are ignited by the incandescent fuel on the other half 
of the grate. During the time of firing, cold air in too 
large a volume enters the furnace through the firehole 
door, and a considerable waste in the chimney gases 
occurs. The damper should be lowered before firing, so as 
to reduce the draught, but this is seldom done except 
by the most careful stokers, when the damper gear is very 
handy. An uneven fire, or one with holes, tends to pro- 
duce the same result, and, therefore, it is not surprising 
that mechanical firing should be resorted to where feasible. 

The other methods are the "spreading" system in 
which the fire is covered uniformly all over with green fuel, 
and the " coking " method in which the green fuel is fed 
in front of the fire-door and after coking is pushed down 
the bars. 



14 meldrum's forced draught furnace. 

The chief features of mechanical stokers are — even fires, 
absence of uneven air supply, uniform combustion, and 
with a large number of furnaces a reduction in the cost of 
labour. 

They are unsuitable for large coal, and work best with 
dry fuel. They work equally well with very inferior fuel. 

They are of two kinds : (1) coking stokers, in which 
the fuel is first coked on entering the furnace, and after 
the volatile matter has been distilled the residue is pushed 
clown the grate and burnt. (2) Sprinkling stokers, in 
which the fuel is evenly scattered or sprinkled over the 
fire without previous coking. The coking stoker gives a 
smokeless chimney, but the sprinkling stoker produces the 
most rapid combustion, and in some cases is more econo- 
mical. It is also possible to adjust the rate of combustion 
with them through a wide range. 

Before describing any mechanical stokers I Avish to draw 
attention to an appliance which reduces smoke, and at the 
same time enables a cheap fuel to be rapidly and econo- 
mically burnt on an ordinary boiler grate. I refer to the 
forced draught produced by a steam jet ; a typical example 
of which is Messrs. Meldrum's appliance in the next illus- 
tration. 

Meldrum's Forced Draught Furnace. — This furnace is 
very simple in construction, and very effective for the pur- 
pose for which it is designed, namely, the burning of inferior 
fuel rapidly and economically. It also has the virtue of 
producing very little smoke. The front casting (Fig. 3) 
is of the usual type, except that the ashpit is closed in, 
and a couple of steam jet blowers inserted in it. Steam is 
supplied to the blowers by a pipe which conveys it from 
the steam space in the boiler into a cast-iron superheater 
over the fire hole door on the inside of the furnace, and 
thence to the blower tubes. The superheating of the 
steam assists in heating the air, tending to improve com- 
bustion ; but its chief purpose is to prevent condensation 
on the boiler plates. To prevent smoke upon the intro- 
duction of green fuel, a door is placed m the casting 
behind the bars to admit a supplementary supply of air 
from the ashpit to the top of the fuel, to enable the volatile 
hydrocarbons to be burnt before they leave the furnace. 
This door is shown at C (Fig. 6). It is operated and adjusted 
by the handle D. 

On account of the noise of the steam jets, which 



MELDRUMS FORCED DRAUGHT FURNACE. 



15 





16 



MELDRUMS FORCED DRAUGHT FURXACE. 




Internal View of Meldrum's Forced Draught Arrangement. 




(® Oj f© ©J (© ©J 




Fig. 5.— Front View of Meldrum's Silent Blower, as Applied 
to Water-tube Boiler. 



MELDRUMS FORCED DRAUGHT FURNACE. 



17 



becomes a nuisance when the boiler is in a confined space 
Messrs. Meldrum have introduced their silent blower ' 



m 



which the air is taken in from a conduit under the floor of the 
boiler house, and the steam jet is also under ground with 
no connection to the atmosphere in the boiler house. This 
has been much appreciated in electric lighting and similar 
works. 




-Sectional Elevation and Sectional Plan of Meldrum's Silent 
Blower. 

Another modification of the silent blower is shown in 
the illustrations, Figs. 5 and 6. Here the blowers are fixed 
in a cast-iron box, which is directly connected to an air 
conduit running along the front of the boiler. The 
adaptation is to a Babcock and Wilcox boiler. 



18 mason's forced draught furnace. 

The application of forced draught produces a greatly 
increased rate of evaporation, generally accompanied by an 
increased duty of the furnace. This, at first sight, might 
appear an anomaly, but we must bear in mind that the 
artificial draught is very easily controlled, and consequently 
the best ratio of air to fuel is easily obtained. Further, 
it is not necessary that the products of combustion should 
leave the boiler flues at a comparatively high temperature 
for the purpose of producing sufficient draught, hence 
means may be adopted to extract as much heat as possible 
from the chimney gases. 

The addition of the steam in the blast from the steam 
jet also probably has something to do with the rapid 
carrying away of heat almost as soon as it is produced by 
combustion. At the high temperature of the furnace the 
hydrogen and the oxygen forming the steam become 
dissociated, and in so doing absorb an enormous quantity 
of heat 

(about 53,000 B.T.U. for every 91b. of steam); 

which is given back again to the products of combustion 
in the combustion chamber further on down the flue, where 
the temperature is such as to allow them to reunite again ; 
thus distributing the heat more evenly over the heating 
surface of the boiler. It is often found that the tempera- 
ture of the products of combustion, as they leave the boiler 
flues for the economiser, is higher with forced draught 
than without it. Here, I believe, lies one reason for the 
same or increased duty with forced draught. The higher 
temperature of the gases surrounding the economiser 
tubes enables heat to pass into the feed water more rapidly 
than at a lower temperature, with the result that the feed 
water receives more heat, and, therefore, enters the boiler 
at a higher temperature, which is well known to conduce 
towards increased economy, similar to that of the live 
steam feed heater. 

Mason's Forced Draught Furnace. — The accompany- 
ing illustrations, Figs. 6a and 6b, show a form of forced 
draught furnace suitable for application to boilers of the 
Lancashire and Cornish type, constructed by W. F. Mason, 
Limited, Engineers, Longsight, Manchester, in accordance 
with Mr. Duff's patents, and which possesses some special 
features. The furnace, it will be seen, is of somewhat 
peculiar construction. It is not furnished with the usual 
firegrate, but has, instead, an oval-shaped tube, built up 



MASONS FORCED DRAUGHT FURNACE. 



19 




20 



mason's forced draught furnace. 




proctor's coking stoker. 21 

in sections extending from the fire door to the bridge 
a little above the bottom of the furnace tube. The 
perforated tube is provided with a vertical longitudinal 
diaphragm, so arranged that the bolts with which the 
various sections are held together are protected from the 
action of the lire. At the same time the diaphragm acts 
as a supporting rib for the tube. The forced draught, 
which is supplied by a steam blower, passes through the 
interior of the tube and escapes through the circumferential 
slits into the mass of lire which is built straight up from 
the bottom of the furnace tube. 

By this arrangement the quantity of fuel which can be 
operated upon is obviously largely in excess of anything 
that can be obtained with the use of an ordinary grate, a 
point of considerable importance when dealing with low- 
grade fuels, since it permits of heavy charges, and hence 
avoids the necessity for firing at frequent intervals and 
the inrush of cold air which then, of course, takes place. 
In starting the fire, ashes are first filled in through the fire 
door up to the level of the top of the blower. A fire is 
then built upon the top of the ashes, and, as more ashes 
are produced, some are raked out from below the furnace 
tube through the ash door. The process of firing and 
cleaning can then be made continuous without any inter- 
ruption in the raising of steam. 

One of the advantages claimed on behalf of this furnace 
over others of a similar kind is that the furnace can be 
operated so that the combustion of fuel is not interrupted 
at the time the ashes are being removed. This not only 
gives steady and continuous steaming, but is of further 
advantage when using inferior fuels, since they contain a 
larger proportion of incombustible matter than good coal, 
and hence cleaning becomes oftener necessary, and it is 
hardly necessary to say that if the fires have to be brought 
to a stand for any length of time in order to rake out the 
ashes the steaming of the boiler is interfered with. 

Proctor's Coking Stoker. — This machine and furnace 
is shown in section and end elevation in Figs. 7 and 8. 
Its action is altogether different to that of the same maker's 
sprinkling stoker. The fuel is fed into a pair of hoppers A, 
from which it gravitates on to feeding rams B, a pair being 
fitted to each furnace. These rams are given a recipro- 
cating motion by the oscillating arms C, which derive their 
motion from the cam plate D, fixed upon the driving shaft 



22 



PROCTOR'S COKING STOKER. 




THE MURPHY FURNACE. 23 

E, which rotates uniformly, being driven by the shaft and 
cone pulleys F through two worms and worm wheels. 

The arm C has a pin fixed in it engaging with and 
driven by the cam plate D, Avhich turns in anti-clockwise 
direction. When the arm has arrived in the dotted 
position, the cam D disengages itself from contact with 
the pin and continues to rotate, leaving the arm C behind, 
until the pin P in the cam engages with the scolloped 
plate H on the arm C, when it returns this arm with a 
greater speed than that at which it was withdrawn. This 
reciprocation of the distributing rams B carries a charge 
of fuel forward towards the fire at the quicker rate, and 
at the same time skims over the top layer of more or less 
coked fuel, distributing it evenly over the fire. The slower 
withdrawing of the rams B leaves the charge of fuel behind 
on the fire, because the head of fuel in the hopper prevents 
the return of the charge. The reciprocating motion of 
every other bar carries the incandescent fuel along the 
grate from which it falls into the ashpit M. The bars 
receive their motion in the same manner as those of the 
sprinkling stoker.* The feeding rams can be worked by 
hand if such should at any time be desired. A steam 
bridge is fitted as in the sprinkler stoker. The firehole 
door K swings about a centre, and is adjusted by the 
handle M. Inside the door at N is a grid for the 
admission of air, a corresponding sliding grid being 
situated at Q. In the right hand furnace, Fig. 8, the fire- 
hole door is removed. 

It is further claimed for this stoker that, on account of 
the shape of the fire, the flames never touch the ring joint 
at the junction of furnace and end plate, consequently the 
joint is not likely to give any trouble. 

The stoker is entirely smokeless when not forced 
beyond the coking capacity of the furnace. 

The Murphy Furnace, manufactured by Messrs. Clench 
and Co., of Chesterfield, is of a novel kind. It is external 
to the boiler, and has its firebars placed transversely in two 
rows, while they slope downwards, at a considerable angle, 
like an inverted roof. 

Fig. 9 shows a transverse section of one of these 
furnaces. On each side of the fire is a coal magazine A from 
which the coal gravitates on to a ledge or coking plate B. 
It is pushed into the fire by pusher plates or castings C, the 

* A description of the sprinkling stoker is given later (p. 33). 



24 



THE MURPHY FURNACE, 







THE MURPHY FURNACE. 



25 



undersides of which are provided with a toothed rack. This 
rack gears with the quadrant of a spur wheel, which is made 
to oscillate slowly; the shaft upon which it is fixed being 
connected to a long oscillating rod D (Fig. 10) by a crank 
and a small connecting link E. This long rod runs across the 
front of one or more boilers, and operates the pusher 
plates as well as the clinker breaker F at the lower ends of 
the fire bars. This latter is driven by means of a ratchet G, 
and thus continues to rotate during the time that coal is 
being fed upon the fire. It breaks up any clinker that 
happens to fall down the bars, by teeth on its exterior 
surface, and prevents the ash accumulating in the lower 



~ i, ....a. 




=3 bH!/- - --■-■-- — 



... -.— -^-i- 



Fig. 10. — Front Elevation of Murphy Furnace as applied to a 
Lancashire Boiler. 



part of the fire. It is hollow and connected to the chinmey 
flue so that a current of air is continually passing through, 
keeping it cool. The bars are made to reciprocate 
slightly by the same mechanism that operates the pusher 
plates, so that the fuel is continually travelling down 
the bars, being coked while at the coking plate near 
the top of the bars. A firebrick arch H covers the fire. Air 
is admitted from the air chamber J above the arch in small 
jets along the top of the green fuel at the skewback, 
and the large number of these small air ducts permits a 
thorough admixture of air and the hydrocarbons given off 
by the distillation of the green fuel during the process of 



26 



THE MUEPHY FURNACE. 



coking, the incandescent coke that is left being burned 
upon the firebars. The heated air and hydrocarbons, after 
mixing together, pass between the incandescent firebrick 
arch above and the incandescent fuel on the bars below, 




and can hardly fail to be thoroughly burnt before they 
emerge from the furnace to the boiler-heating surfaces. 
'. ] This permits of the most complete combustion, and 
consequently an entire absence of smoke. 
.-.-; i Figs. 11 and 12 show the application of this furnace to a 



water-tube boiler, for which it seems well adapted. 



Figs. 



THE MURPHY FURNACE. 



27 



10, 13, and 14 also show one way of applying it to a 
Lancashire or Cornish boiler. 

The channel through which the air enters above the 
firebrick arch is well shown in these figures. The arched 
covering to the furnace is hollow, the cavity between the 
outer and inner parts being used as the channel through 




V 




Fig. 12. — Front Elevation of Murphy Furnace as applied to a 
Water-tube Boiler. 

which the air must pass on its way to the green fuel on 
the coking plates. 

Heat that would otherwise be radiated to the atmos- 
phere is thereby caught by the incoming air, and while 
radiation is diminished, the higher tenmerature of the air 



promotes more perfect combustion. 



28 



THE MURPHY FURNACE. 




THE MURPHY FURNACE. 



29 



The chief peculiarity of this furnace is the length of 
aperture through which green coal can be fed to the fire ; 
allowing a thin layer and perfect coking before it comes 
well on to the firebars. The same also allows a very perfect 
mixing of the air, and fuel distillates, which tends to 
prevent smoke. 




Fig. 14 — Longitudinal Section of Murphy Furnace as applied to a 
Lancashire Boiler. 



The fuel is supplied to the magazine through the doors 
M shown in the front of the boiler, and the air supply to the 
coking plates over the fire-brick arch is regulated by a 
grating for the purpose on the front of the boiler. 

Recently the makers of this furnace have had one of 
them tested by Professor Ripper, and one paragraph of his 
report, referring to the prevention of smoke, is very 
pertinent to the question, and I venture to repeat it here. 



30 meldeum's "kokee" stokee. 

" The chimney was closely observed during the trials, 
and was found to be perfectly free from smoke. Nor was 
this due to the composition of the fuel (Boythorpe slack), 
for it was found that by raking down the green fuel from the 
coking plates (a procedure contrary to the rules prescribed 
for working the furnace) dense volumes of black smoke 
were emitted from the chimney." 

At times, faint grey smoke was observed for periods 
not exceeding 1J minutes, generally following any dis- 
turbance of the fires. It was found that the fires might 
be raked to any extent without causing smoke provided 
that the green coal was not prematurely taken from the 
coking plates. To further test the furnace as a smoke 
burner, a short trial was subsequently made with Shire Oak 
slack. With this coal, although it is noted for smoke 
making, the chimney could be kept perfectly free from 
smoke without any unusual precautions being taken. 

In the trials above referred to the rate of combustion 
was such as to consume 15 lb. and 23 lb. of fuel per square 
foot of grate per hour. Up to 50 lb. can be burnt in this 
furnace, which should be well adapted for the destruction 
of refuse, with some little modification. 

Meldrum's " Koker " Stoker. — The mechanical stoker 
introduced by this firm is of the coking type. (See 
Figs. 15 and 16.) It is extremely simple, and is arranged 
for use with the same makers' s}^stern of forced draught. 
Fuel is fed into a hopper A, at the base of which is a cast- 
ing B in the shape of a quarter cylinder, which is fixed 
to, and oscillates with, a spindle driven by a crank and 
connecting rod, as shown in the front view of the stoker 
at C. The backward movement of the quarter cylinder 
or rocking plate allows the fuel to fall towards the 
opening into the furnace, while the forward motion pushes 
the fuel on to the coking plate D. The fire bars have a 
wave-like contour, for the purpose of breaking up any 
clinker that may form on them. They are all moved for- 
ward together, but are withdrawn one by one, thus leaving 
the incandescent fuel that much nearer the clinker cham- 
ber. The bars are operated by a series of cams on a 
hexagonal shaft E traversing the front of the boiler and 
driven by a belt from an overhead shaft and through worm 
gear in the box F. 

The blowers H are of the silent type, and deliver into a 
shallow box K opening directly into the ashpit under the 



31 




32 MELDEUM'S " KOKEE " STOKEE. 

bars. Steam is supplied to the blowers by a pipe M, which 
traverses the ends of the side flues for the purpose of 
superheating it. 

By a veiy simple arrangement this stoker is able to 
overcome the difficulty which some coking stokers labour 
under, while relying on natural draught, of not being 
capable of being forced. The fuel on the coking plate is 
then propelled on to the bars so rapidly that the coking 
process has not time to approach completion, with the 
result that the green fuel travels down the bars in too great 
a quantity and smothers the fire. To get over this difficulty 
Messrs. Meldrum have arranged a perforated coking plate 
D to receive the fuel from the pusher, the perforations 
allowing a supply of air to percolate through the green fuel 
at the back of the fire from the ashpit, and thus aid combus- 
tion in that region, which allows of the fuel being worked 
forward more rapidly on to the bars, but in a state of coke 
instead of green fuel. The makers prefer to arrange for a 
supplementary supply of air just above and behind the 
coking plate at X, because this supply can be nicely regu- 
lated to suit the rapidity of combustion and prevention of 
smoke. The handwheels W are for the purpose of regulat- 
ing the supply of steam to the blowers. 

Messrs. Meldrum have burnt as much as 40 lb. per 
square foot of grate per hour, without smoke, with this 
stoker. 

Appended are details of a test of a " Koker " stoker 
applied to a Lancashire boiler : — 

Date of test Sept. 9, 1898. 

Duration 8 hours. 

Size of boiler 27ft. 6 in. by 7ft. 6 in. 

Fuel slack. 

Total fuel burnt 7,0001b. 

Fuel burnt per hour 875 lb. 

„ ,, per sq. ft. grate 29*1 lb. 

Total ash 2341b. 

„ per cent 3*3. 

Total water evaporated 67,000 lb. 

Water per hour 8,375 lb. 

„ lb. fuel, from cold feed 9 '57 lb. 

from and at 212 deg... 11 -02 lb. 

Steam pressure 65 - 6 lb. 

Feed temperature 99 '9 deg. Fah. 

Temperature of downtake gases ...980 deg. Fah. 



proctor's sprinkling stoker. 33 

Orsat gas apparatus readings : 

C0 2 11 '9 per cent. 

7 '4 per cent. 

Observations taken every half hour with Orsat 
apparatus. 

Proctor's Shovel or Sprinkling Stoker. — The main 
principle of this machine is the feeding of the fuel into a 
small box, from which it is kicked on to and scattered over 
the fire by a shovel or beater. 

A longitudinal section of the machine and furnace is 
shown in Fig. 17 and a front view in Fig. 18. 

Fuel is fed by hand or by mechanical means into the 
cast-iron hopper A, from which it gravitates into the ram 
box B, which communicates with the shovel boxes C. It 
is pushed into the shovel boxes by the ram I in definite 
quantities at regular intervals, and is then scattered over 
the fire by the sudden forward motion of the shovel W. 
The tappet cams compel the sprinkling shovel to withdraw 
different amounts at three consecutive movements, thus 
giving to the coal three different impulses and completely 
covering the whole grate. The ram I receives its reciprocat- 
ing motion from the arm Y, fixed upon the short shaft 
T, which in turn is actuated by the arm N. This latter 
arm is made to oscillate by a pin in the disc 0, which 
is driven continuously by the vertical shaft J, which is 
driven by the shaft K. This latter shaft is driven by a 
rope on the speed cones L to allow of varying rates of 
feed, and consequently of combustion. 

The shaded pin fixed in the rotating disc engages in 
the slot of the arm P, and gives it an oscillating motion, 
turning about a pin not shown in the figures. The arm P 
is really a bell crank lever, having a couple of horizontal 
arms, with teeth at their extremities which gear with teeth 
on the ends of the arm N. In this way a reciprocating 
motion is given to the pusher rams I. 

The shovels W are made to recede from the fire by 
tappet cams Z (see Fig. 19) coming in contact with a 
tappet arm F, fixed upon the shovel spindle M in 
the tappet box X, which also contains lubricant, that is 
continually supplied to the parts subject to wear by a 
chain in the ordinary way. After the cam shaft has turned 
through a given angle, the tappet arm is released, and the 
shovel, shovel shaft, and attached arm Y are suddenly 
moved together by the recoiling of the helical spring H, 



34 



PROCTOR S SPRINKLING STOKER. 




PROCTORS SPRINKLING STOKER. 



35 



and coal is sprinkled thereby over the fire (see Fig. 20). 
The firedoor S is moved and adjusted by the lever R, and 
is used for hand-firing if necessary, when the mechanical 




Fig. 19. — Tappet Cam Arrangement ; Proctor's Sprinkling Stoker. 

stoker is not being used, and also for the admission of 
supplementary air above the fuel on the bars. 

The fire-bars Q are supported at their extremities by 
cast-iron bearing plates, that at the back end of the furnace 




m H 



Fig. 20.— Showing Action of Sprinkling Shovel ; Proctor's Stoker. 



U containing a channel through which steam passes from 
the pipe E. The object of this steam bearer is to prevent 
the bar ends from burning away, and allowing an active 
fire to be kept up the whole length of the bars, without 



36 



BENNIS SPEIXKING STOKER. 



fear of burning the backs down and thereby reducing the 
duty at that part of the furnace. Only a relatively small 
quantity of steam is used to protect the back end of the bars. 
Every alternate bar is made to reciprocate constantly by 
the rocking shaft and arms 6, which are driven by the pin 
2, gearing in the slot of the arm 5. The pin 2 is fixed in 
the rotating disc secured upon the shaft 8, and driven by 
a worm on the vertical shaft J. The reciprocating motion 
of the alternate bars prevents clinker from adhering to 
them, and eventually delivers it over the steam bearer into 
the ashpit, from which it may be withdrawn at intervals 
through the flap door. 




Fig. 21. 



-Longitudinal Section of Feeding Arrangement ; Bennis' 
Sprinkling Stoker. 



It is not claimed for this stoker that smoke is entirely 
avoided, but with ordinary attention very little smoke need 
be made. The duty of the furnace is very good, and is 
specially adapted for work in which a sudden and heavy 
demand for steam occurs. 

Bennis' Sprinkling Stoker. — Fuel is fed into the 
hopper A, from which it gravitates on to the plate B 
(Fig. 21), which is made to move forward periodically 
by the cam D and bent lever C (Fig. 22). The cam D is 
adjustable by means of the lever E and screw F, so that 
any quantity of fuel from J lb. to 2 lb. can be pushed 
forward into the shovel chamber K at each forward stroke 
of the sliding plate B. In Fig. 23 will be seen a curved 



BENNIS SPRINKLING STOKER. 



37 



arm M, swinging about a pin 0, having on its lower 
extremity a shovel or striker L. The arm M is attached to 




Fig. 22.— Sectional Plan of Feeding Arrangement ; Bennis' 
Sprinkling Stoker. 



a piston rod R, which carries the piston U. This piston is 
propelled forwards by the helical spring V in the cylinder 




Fig. 23 — Showing Action of Sprinkling Shovel ; Bennis' Stoker. 



T, which oscillates about a fixed centre Z attached to the 
fuel box. The shovel arm is propelled backwards against 



38 BENNIS' SPRINKLING STOKER. 

the spiral spring by the arms of the cam Q fixed upon the 
shaft Y. This shaft, which also contains the cam D. is 
continually and uniformly rotated by a worm gear in the 
gear box on one side of the boiler. It derives its 
motion from an overhead countershaft driving the speed 
cones on the outside of the gear box. 

After a charge of coal has been deposited in the shovel 
chamber by the plate B, the shovel arm is released from 
one of the arms of the cam Q, and the spring Y propels it 
forward, suddenly striking the fuel on to the fire. 

The shovel is brought to rest silently and without 
shock by compressing between it and the cylinder head 
the air in that end of the cylinder. This naturally prolongs 
the life of the striking mechanism considerably. It will 
be noticed that the arms of the cam Q are of different 
sizes, and consequently the shovel and piston U is made 
to travel different amounts, thus producing four different 
amounts of compression of the spring Y. This variation of 
compression produces a corresponding variation in the 
impulses with which the fuel is struck over the fire, with 
the result that the fuel is delivered on to four different 
zones of the grate, producing an even distribution of fuel. 
This, the makers claim, secures that each unit of grate 
area shall burn an equal amount of fuel, and consequently 
contribute an equal amount towards the evaporation of 
the feed water. At the same time it permits of very rapid 
combustion, and an exceedingly high and uniform tem- 
perature in the furnace. This, of course, conduces 
towards economy. A front elevation of this stoker is 
shown in Fig. 24, and a side elevation in Fig. 25. 

The firebars upon which the fuel is burnt are all 
moved forward together by a cam shaft for the purpose, 
and then withdrawn one at a time. The forward 
motion of the bars carries the fuel forward bodily, 
while the backward motion of each bar singly does not 
carry any of the fire with it, so that the ash and clinker 
is always being carried towards the ashpit, and the 
clinker has not the opportunity of cementing itself on to 
the bars. Each bar is hollow, and contains along its top 
surface a series of grids with narrow apertures. Air is 
blown into the bars by a steam jet, and issues through the 
grid apertures into the fire, producing an even distribution 
of the blast. The apertures being very narrow the ash 
does not get into the bar in any quantity. 



BENN1S SPRINKLING STOKER. 



39 




40 RANSOME AND RAPIER'S SPRINKLING STOKER. 

Trial of Bennis' Compressed Air Furnace and Sprinkling 
Stoker. July 13th, 1898. 

Lancashire boiler 9ft. diameter, 30ft. long, 3ft. Tin. flues 

Heating surface 1,200 sq. ft. 

Duration of trial 8 hours 

Fuel used Sharlston Nuts 

Coal burnt per hour 1,637 lb. 

Coal per square foot of heating surface per hour... 136 lb. 

Steam pressure 671b. per sq. in. 

Water evaporated per hour 16,250 lb. 

Water evaporated per lb. fuel at boiler pressure ... 99 lb. 
Water evaporated per lb. fuel from and at 212 deg.. 10*18 lb. 

Temperature of water entering economiser 100*3 deg. Fah. 

Temperature of water leaving economiser 222 deg. Fah. 

Temperature of downtake gases 1,325 deg. Fah. 

Temperature of gases entering economiser 678 deg. Fah. 

Temperature of gases leaving economiser 370 deg. Fah. 

Temperature of atmosphere 74 deg. Fah. 

C0 2 11-8 percent 

Oxygen 68 per cent 

Nitrogen 814 per cent 

Calorific value of coal determined from analysis ... 14,374 B.T.U. 
Efficiency of boiler and economiser 84-6 per cent. 

In this trial the coal was burnt at the rate of over 301b. per square 
foot of grate per hour. 

Ransome and Rapier's Sprinkling Stoker. — A front 
elevation of this stoker is shown in Fig. 26, as applied to a 
Lancashire boiler, while a longitudinal section of one of 
the furnaces is shown in Fig. 27. A detail of the 
sprinkling shovel arrangement is shown in Fig. 28. 

Fuel is fed into the hoppers A in the usual manner, 
and gravitates on to a pusher feed-plate C, in the box B. 
This pusher is given a reciprocating motion by a small 
crank not shown in the figure, but driven by the series of 
spur wheels on the right of each hopper, the lowest wheel 
being secured upon the little crank shaft, while the highest 
wheel is fixed upon the cam spindle running along the 
front of the boiler behind the fuel hoppers. 

The cam shaft derives its motion from the overhead 
countershaft W, through the cone pulley S, and two pairs 
of worm and worm wheels. 

The travel of the pusher plate C is regulated by turning 
a thumb nut inside the box B, the door of which is held by 
a spring catch. The little crank works in a vertical slot in 



42 



RANSOME AND RAPIER S SPRINKLING STOKER. 



the pusher plate, the width of the slot being adjustable by 
turning the thumb nut. Screwing up the nut enlarges the 
slot, and consequently the crank pin travels further without 
touching the sides of the slot, and therefore the travel of 
the pusher plate is diminished. If the nut is unscrewed 
the sides of the slot approach each other, diminishing the 
lost motion, and the travel of the pusher is increased. In 
this wa}^ the rate at which the fuel is fed upon the fire is 
easily regulated to suit the demand for steam. 




Fig. 28.- 



■ Section of Sprinkling Shovel Arrangement 
Rapier's Stoker. 



Ransome and 



The pusher plate delivers a charge of coal in front of 
the sprinkling shovel, and the rapid forward movement of 
the shovel kicks the fuel on to the grate. This action is 
more readily seen on referring to Fig. 28. The shovel is 
supported by a pair of arms, one on each side, which swing 
about a fixed centre. To the same spindle is keyed the 
arm G, which is coupled to a small piston in the casing or 
cylinder E by a short connecting rod. In the cylinder E 
are two helical springs, one on each side of the piston ; one 
for giving motion to the sprinkling shovel, and the other 
for taking up the recoil and bringing the shovel to rest. 



THE CASS COKING STOKER. 43 

The shovel is withdrawn and one of the above springs 
compressed by the cams F coming into contact with 
suitable arms on the shovel spindle. These four cams are 
of different sizes, for withdrawing the shovel corresponding- 
distances, and thus imparting to the coal four different 
impulses, for the purpose of spreading it uniformly over 
the fire. The bars are pushed forward into the fire all 
together, and withdrawn one by one, by the cams threaded 
on the square shaft J, driven by the worm and worm- 
wheel T, on the right of the boiler. The back ends of the 
bars rest and slide upon a bearing-plate M, and in the 
illustration is shown a small steam pipe which provides 
jets of steam which play upon the under side of the bars, 
and prevent clinker from adhering to them. One of these 
stokers, which the writer saw at work, had a similar pipe 
in connection with the front bearer for the same purpose. 
The bars in this instance, which were stated to have been 
in use for twelve months, were perfectly clean, and appeared 
as sharp at the edges as when they left the mould. North 
country small coal was being used, and there was an entire 
absence of smoke at the chimney top. 

The cam shaft is raised well above the fire, and all its 
bearings can be easily and efficiently lubricated. This 
applies to the other bearings as well. 

The Cass Coking- Stoker. — This mechanical stoker is 
shown in Figs. 29 and 30. The regulation of the fuel is 
accomplished by the wedge in the fuel hopper, by whose 
position the size of the aperture through which the fuel gravi- 
tates to the fire is controlled. It is supported by a chain 
shown in Fig. 28b, and can be adjusted by the hand lever on 
the side of the hopper. After falling' on to the coking 
plate the fuel is carried along by the reciprocating motion 
of the bars, being coked before it gets well on to the fire. 
The ash and cinder is delivered over the ends of the bars 
into the cinder chamber. The bars are worked by a pair 
of cam shafts in a very simple manner, as shown in the 
figure, and it will be noticed that the front end is sup- 
ported on a beam resting on a couple of uprights, so that 
there is no actual connection to the boiler plates or neces- 
sity for drilling holes. The firebrick arch immediately 
over the coking plate tends to assist and perfect the coking 
action, and at the same time protect the ring joint in the 
front of the furnace. The illustrations, being clear, need 
no further description. 



44 



THE CASS COKING STOKER. 




Fig. 29. — Front Elevation ; Cass Coking Stoker. 




Fig. SO.— Longitudinal Section ; Cass Coking Stoker. 



SMOKELESS COMBUSTION OF FUEL. 45 

Conclusions. — We may say that for economical and 
smokeless combustion of fuel it is desirable that — 

(1) The air to support combustion should be thoroughly 
intermixed with the constituents of the fuel to be burnt 
at the time of ignition, and especially is this the case with 
the hydrocarbons distilled from green fuel as it is put on 
the fire. 

(2) The air supply must be in excess of the theoretical 
quantity, but the excess should be carefully regulated not 
to waste more heat than is absolutely necessary in the 
chimney gases, 

(3) The air should be delivered to the fire at as high 
a temperature as possible, and should be regulated to the 
needs of combustion. 

(4) The temperature of the furnace should be as high 
as possible, so that the heat of combustion shall be rapidly 
transmitted to the water. 

(5) The firing should be done uniformly, and a uniform 
thickness of fire is very desirable. The firehole door 
should be opened as seldom as possible, and all air leakages 
should be stopped. 

(6) The heating surfaces of the boiler should not be 
too near the gases when they are igniting, as the trans- 
mission of heat rapidly cools the gases and may prevent 
complete combustion. 

The problem of burning fuel without smoke is a com- 
paratively simple one, as may be gathered from what has 
been already said, if the rate of combustion is of no con- 
sequence. Natural draught coking stokers can and do 
burn all sorts of fuel with an entire absence of smoke, 
except while the fires are being cleaned ; but they do it 
on a comparatively low and uniform rate of combustion. 

They must not be forced, or the fires become smothered 
with green fuel, and smoke must appear, after which they 
2fo right out. Further, coking stokers with natural draught 
cannot be started suddenly and made to furnish a quantity 
of steam in case of emergency. 

It is on this account that they are unsuitable for electric 
lighting stations laid down in the heart of a town, where 
land is expensive, and a large margin of boiler power cannot 
be secured. Many existing central stations labour under 
this difficulty, and cannot obtain more accommodation at 
any cost, with the result that their boilers have to be forced 
to their utmost limit to furnish sufficient steam during the 
heavy load. They are at the same time handicapped by 



46 ESTIMATING DENSITY OF SMOKE. 

being prevented by the local authorities from producing 
smoke. 

It is here that the best hand firing must be resorted to, 
or sprinkling stokers adopted, which, with a little care, 
produce little smoke, and at the same time permit of a 
wide range in the rate of combustion. The one thing to 
be looked after in a sprinkling stoker, as with hand firing, 
is that the feed of fuel and the draught shall be commen- 
surate. If the fuel supply is reduced with too much 
draught the thin fire may burn into holes, and a loss of 
economy will immediately begin ; whereas, if the draught 
is small with a heavy feed, smoke must be produced. 

With hand firing, the fires are carefully thickened as 
the period of heaA~y load approaches, so that when 
necessary, they may be opened out and the maximum 
evaporation carried on for the short interval of heaviest 
loads, principally by the thick mass of incandescent fuel. 

Dense black smoke can always be avoided if the proper 
means are adopted to prevent it ; but the conditions under 
which many steam boilers have to be worked do not per- 
mit of an absolutely smokeless chimney. 

Mechanical stokers are not intended to be used with 
large coal, and, generally speaking, the same applies to 
forced draught, but with these appliances small coal and 
very inferior kinds of fuel, such as slack or coke breeze, 
may be burnt with ease and economy. 

It must not be forgotten that the domestic hearth is 
often a most wanton offender, and the smoke produced by 
it per pound of fuel burnt generally far exceeds that of 
any steam boiler. This must be so from the crude manner 
in which combustion is expected to take place. 

Estimation of the Density of Smoke. — There is 
considerable difficult} 7 in estimating the quantity of smoke 
and its density as it emerges from a chimney. Probably 
the best method so far suq-aested is that of Kino-elmann's. 
He has drawn five diagrams, Fig. 31, consisting of black 
lines of varying thickness and distance apart, upon pieces 
of white cardboard ; and these are suspended in a good 
light 50 ft. or 60 ft. from the observer, but so situated 

o ... 

that the smoke to be estimated is seen near or behind the 
diagrams. Whichever diagram appears to coincide most 
nearly with the density of the smoke, that is the compara- 
tive number of the density. The following are the 
dimensions from which the diagrams can be constructed. 



EINGELMANN SMOKE TEST. 



47 

































































































































* 





































































































































































































































































































































































































































































































































































































































































































































































































3 4 

Fig. 31. — Ringelmann Smoke Test. 



48 PAKIS SMOKE COMMISSION TRIALS. 

Smoke. 

No. All white None. 

,, 1 Black line, 1 mm. thick, white spaces, 9 mm. wide, light grej. 
,,2 „ „ 2-3 „ ,, „ 7-7 „ darker grey. 

,, 3 ,, ,, 3*7 ,, ,, ,, 6*3 ,, very dark. 

,, I ,, „ 5-5 ,, ,, ,, 4'5 ,, black. 

,,5 All black dense black. 

Reduced copies of four out of the five scales are shown in the accom- 
panying Fig. 31. 

Smoke Commissions. — The principal commissions insti- 
tuted for the purpose of inquiring into the smoke 
nuisance were the Prussian 1894, English 1895, and the 
Paris Municipal 1897. The last of these did the most 
thorough work, and it is proposed to give here a brief 
resume of it. 

By a resolution of the Municipal Council of Paris, of 
June 2nd, 1894, a Technical Commission was formed to 
draw up a programme for a competition of smoke consum- 
ing apparatus, to take charge of the trials, and to draw up 
a report of the trials. 

After three and a half years the Commission finished 
its work and presented its report, which extends through 
a couple of hundred pages of printed matter, including 
diagrams. 

The report is divided into five parts : — 

1. Analysis of the different projects. 

2. Carrying out of the experiments. 

3. Detailed results of the trials. 

4. Historical summary. 

5. Examination of the results of the competition, 

and conclusions. 

Competitors were requested to send in to the Commis- 
sion full information respecting the particular system 
which they intended to present for competition. This 
information was examined in detail by the Commission, 
and as a large number did not appear to present sufficient 
chance of success, these latter were discarded. There then 
remained 30 projects which appeared to warrant further 
investigation. 



PARIS SMOKE COMMISSION TRIALS. 



49 



It was then decided to form a number of sub-commis- 
sions to visit actually existing examples of the remaining 
30 projects, for the purpose of examining them at work and 
reporting upon them, with a view of further elimination 
before the final trials were decided upon. The result was 
that 10 projects were finally retained for trial. 

These 10 competitors were then advised of the Com- 
mission's decision, of which eight agreed to submit 
apparatus for trial. 

Each different apparatus was then allotted a definite 
date for trial, which was designed to last for one month. 




Fig. 32. — Transverse Section of Boiler Setting. 

There were originally 110 schemes submitted, of which 
76 were French, 19 English, four German, and three 
American. Three prizes of 10,000 francs, 5,000 francs, 
and 2,000 francs were offered for the three most successful 
schemes. The different schemes were applied to two out 
of three similar boilers belonging to the municipality of 
Paris, and used for supplying steam to a pair of pumping 



The boilers were all of the same kind and dimensions, 
views of one of which are given in Figs. 32 to 34. The 
large cylinder contains a number of smoke tubes, but these 
are not shown in the sketch. 



50 



PARIS SMOKE COMMISSION TRIALS. 



The principal dimensions were : — 

Upper Brums— Diameter T38 metres 

Length 3'5 

Lower Drums — Diameter -72 

Length 53 

Smoke Tube* — Number 50 

Outside diameter 80 m.m. 

Thickness 3 

Heating Surface 68 sq" m. 

Grate— Length 115 metres 

Width 1-3 

Area 1*5 sq. m. 

GMmney — Height 30 metres 

Sectional area at top -385 sq. m. 

Sectional area at base 1*21 



Y/////////V///ZZ7/ 



JZ% 



o o 

- ' w 







V> & V ^ 



_M4^Am^zML 



1 



Fig. 33. — Sectional Plan of one of the two Boilers experimented upon. 




Fig. 34. — Longitudinal Section of Boiler SettiDg. 
LIBRARY 
. ENGINEER SCHOOL. 



PARIS SMOKE COMMISSION TRIALS. 51 

Fuel. — The fuel used was briquette d'Anzin, of ordinary 
quality, which was described in the report as " passably 
smoky/' but it possessed one feature which recommended 
it for these trials — namely, uniformity. A number of 
analyses gave an average of 8*2 per cent ash and 17'8 
volatile matter. 

Each competitor was informed of the particular time 
allotted to his apparatus for trial, and every opportunity 
was afforded for thoroughly testing the capability of each 
contrivance. 

Four official trials were carried out with each apparatus, 
each trial beginning at eight o'clock in the morning, and 
terminating at six o'clock in the evening. 

1st. Moderate rate of combustion, with only one engine 
at work, the apparatus being under the control 
of a stoker furnished by the competitor. 

2nd. Same as 1st, but stoker furnished by the adminis- 
tration. 

3rd. Same as 1st, but at higher rate of combustion. 

4th. Same as 3rd, but with stoker furnished by the 
administration. 

If preferred, the competitor need not furnish a stoker 
for trials Nos. 1 and 3, but could direct one of the stokers 
of the administration if he preferred. 

In addition to the official trials mentioned above, each 
apparatus had to work continuously for one month, the 
official trials taking place within that time. 

Preliminary Experiments. — It was thought necessary 
to carry out a preliminary trial on one of the boilers, with 
the ordinary grate, bars, &c, for the purpose of checking 
the apparatus about to be used, and as a means of familiar- 
ising the observers with their work. 

These preliminary trials were conducted in every way 
by the same observers, and in precisely the same manner 
as the competitive trials. 

Estimation of Smoke. — It was considered by the Com- 
mission that some direct means of estimating the volume 
and density of the smoke emitted from the chimney was 
most desirable. For obtaining a fairer average it was 
decided to take the mean of the observations of two 
separate and careful observers, stationed in two opposite 



52 



PAEIS SMOKE COMMISSION TRIALS, 



positions, one about 300 metres to the north, and the other 
300 metres to the south of the chimney. In both instances 
the observers were practically on the same level as the top 
of the chimney. 




Fig. 35. — Plan of Recording Apparatus. 

The five gradations used were — 

1. No smoke. 

2. Faint smoke. 

3. Medium smoke. 

4. Black smoke. 

5. Opaque smoke. 




Fig. 36.— End View of Recording Cylinder. 

Each observer recorded his estimation of the intensity 
of the smoke by sliding the handle (Figs. 35 and 36) until 
the pen was in the position required by the observer, 
which could be seen upon the graduated paper placed on 



RESULTS OF PARIS SMOKE COMMISSION TRIALS. 



53 





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54 PARIS SMOKE COMMISSION TRIALS. 

the drum, which was rotated by clockwork. The distance 
from the left-hand margin denotes the intensity of the 
smoke, and the area denotes the quantity. 

It was especially remarked in the report that both the 
details and the averages of the two sets of records agreed 
remarkably well, showing the probability of the accuracy 
of this mode of estimation. 

The other quantities in connection with the trials were 
measured in the usual manner. 

The Commission's Award. — It was the opinion of the 
commission that the schemes of Mr. James Proctor and 
M. Donneley proved themselves practically equal in value 
as smoke consumers and evaporators of water, and they 
awarded them each second prize and 5,000 francs. The 
third prize and 2,000 francs was awarded to M. Ckiandi. 

It is gratifying to find Mr. Proctor's machine appearing 
at the top of the list, especially as he was practically the 
pioneer of successful machine stoking. 



DESTRUCTOR FURNACES. 



Meldrum's Refuse Destructor. — A subject which must 
be of great moment to those interested in sanitary 
matters is that of the successful destruction of domestic 
refuse, and on this account I venture to describe a few 
forms of destructor which have proved to be successful 
and economical^ The accompanying illustrations show the 



TIPPING PLATFORM 




Fig. 37.— Section of Refuse Hopper, Grate, and Tipping Platform ; 
Meldrum's Refuse Destructor. 

K. 

construction of a destructor, and its application to the 
generation of steam in Lancashire or Cornish boilers, made 
by Messrs. Meldrum Bros., of Manchester. 



The green refuse is tipped into the containing hopper 
from the tipping platform, Fig. 37. It is withdrawn through 
vertical sliding doors at the foot of the hopper, from 
which it is shovelled by hand on to the destructor furnace 
grates. These grates are placed side by side (Fig. 38) so 
that any unburnt gases emitted from one grate during the 



56 meldrum's refuse destructor. 

n 




-D 



MELDEUMS REFUSE DESTRUCTOR. 



57 







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58 meldrum's refuse destructor. 

process of charging will be cremated during their passage 
over the incandescent matter on the grates between it and 
the combustion chamber, Fig. 39. The grates being so 
situated, the products of combustion from all the grates 
become thoroughly mixed, resulting in a practically 
uniform temperature throughout the furnace. This is of 
much importance on account of the non-uniformity of 
the material to be burnt, and of the fact that it often 
contains much moisture, and is of very low calorific 
value. The products of combustion after leaving the 
furnace enter a spacious combustion chamber in which 
is deposited much of the dust and cinder that may be 
carried over with the products of combustion. The tem- 
perature of this chamber is about 2,000 deg. Fah. After 
leaving this chamber the ^ases circulate through the flues 
of a boiler and give up their heat to generate steam which 
may be used for various purposes. At the end of the 
boiler is situated a regenerating air heater. This consists 
of a battery of cast-iron pipes surrounded by the products 
of combustion on their way to the chimney. Through 
these pipes travels the air which is used to support com- 
bustion, and which is thereby raised in temperature some 
200 deg. before it reaches the refuse furnace. This very 
materially assists the rapid combustion of damp refuse. 

The necessary draught is produced by Messrs. Meldrum's 
steam jet blowers as applied to boilers in general. The 
clinkering is much facilitated by the adoption of tipping 
bars or dead-plate (Figs. 37 and 40), which can be so 
arranged that the clinker and cinder is dropped into a 
trolley running along the ashpit, which, after being 
allowed to cool, may be withdrawn at the convenience of 
the attendant, thus getting rid of the nuisance of cooling 
the clinker with water in front of the cells. 

A large door is provided at one end of the furnace for 
the introduction of condemned mattresses and similar 
refuse (see Fig. 38). 

Xo fuel is used in these destructors, so that there is 
no expense incurred in that direction ; at the same time 
those plants so far put down have furnished a supply of 
steam for sewage and water pumping, sewage presses, and 
the generation of electricity. The rate of destruction of 
refuse varies from 451b. to 551b. per square foot of grate 
per hour, and repeated tests have shown that the water 
evaporated from and at 212 deg. per pound refuse has 
varied from 1*6 to 21b. with unscreened refuse. 



MELDRUMS REFUSE DESTRUCTOR. 



59 




II 





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60 



MELDRUMS REFUSE DESTRUCTOR. 




meldrum's refuse destructor. 61 

The results of a test at the Rochdale Corporation 
Works are given below : — 

Date March 1st, 1895. 

Duration 6 hours. 

Refuse burnt per sq. ft. grate per hour 47*3 lb. 

Water evaporated per pound refuse from and at 
212 deg 1-97 lb. 

Number of boilers used .2. 

Water evaporated per hour 7,012 lb. 

Steam pressure 1131b. per square inch. 

Size of boilers (Lancashire) 30 ft. by 8 ft. 

C0 2 15*9 per cent. 

CO ...None. 

Free oxygen 22 per cent. 

Highest observed temperature combustion 
chamber 1,980 deg. Fah. 

Lowest observed temperature, combustion 
chamber 1,290 deg. Fah. 

Cost of labour for burning refuse 7Jd. per ton. 



The doors to the furnace are of the lifting type, as 
shown in Fig. 42. 

It is claimed for this system of firing that the refuse is 
only handled once instead of three times, as in the over- 
head system of charging, where the refuse is first dried, 
then fed to the furnace and then levelled. The makers 
state that actual experience has proved a saving in labour 
over the overhead system of charging. 

The records of three other tests carried out at the 
Hereford Sewage Works are given on page 63. The fuel 
was entirely unscreened ashpit refuse. 

The size of the Lancashire boiler was 22 ft. by 6 ft. 6 in. ; 
flues, 2 ft. 9 in. diameter. 



62 



meldeum's eefuse desteuctoe. 




■«*mmm+. 



Fig. 42. — Furnace Doors ; Meldrum's Destructor. 




Fig. 43. — Longitudinal Section of Furnace, Showing Steam 
Jet Blowers ; Meldrum's Destructor. 



MELDRUMS REFUSE GAS1FIER. 



63 



The temperatures and the analyses of the chimney gases 
given below are each the average of about twenty obser- 
vations. 

Test Made with a Meldrum Refuse Destructor at the 
Hereford Sewage Works. 



Date of test ... 

Duration of test 

Weight burned per hour 



1898. 1898. 1898. 

May 4. May 5. May 6. 

10 hours. 10J hours 10 hours 



1,9761b. 1,8551b. 



Weight burned per sq. ft. of grate area 
per hour 

Percentage of clinker and ash 

Percentage of moisture 

Water evaporated per hour 

Water evaporated per lb. of refuse (actual) 

Water evaporated per lb. of refuse from 
and at 212° F 

Temperature of feed water 

Average steam pressure 

„ ,, ,, at blowers 



1,971 lb. 



54-88 lb. 51-52 lb. 54-75 lb. 

33-9% 35-7% j 25-6% 

24-5% 27-0% | 25-0% 

2,6251b. 2,4941b. 2,9801b. 

j 1-32 lb. 1-34 lb. j 1-51 lb. 

| I 
1-58 lb. I 1-60 lb. 1-82 lb. 

48° 48° 48 s 

70 lb. 70 lb. 71 lb. 

641b. 641b. 651b. 



Average air pressure under grates by 
water gauge 

Chimney pull, by water gauge 



Temperature in combustion chamber, by 
copper test 

Temperature of waste gases, leaving 
damper 

Percentage of carbonic acid (C0 2 ) by 
Orsat apparatus 

Percentage of free oxygen (O) by Orsat 
apparatus 

Percentage of carbonic oxide (CO) by 
Orsat apparatus 



1-45 in. 
fin. 
Over 



1-37 in. 
fin. 
Over 



1-82 in. 
fin. 
Over 



2,000° F. i 2,000° F. 2,000° F. 



611 F. 

14-92% 
5-40% 
nil. 



639 F. 
16-83% 

3-54% 

nil. 



715 F. 

16-38% 
3-74% 
nil. 



64 mason's kefttse gasifier. 

Mason's Refuse Gasifier.— The accompanying illus- 
trations, Figs. 44 — 51, show a form of destructor furnace 
or gasifier constructed in accordance with Duff's patents, 
which possesses a number of special advantages. 

The general design of the destructor-furnace — or, more 
strictly speaking, gasifier — is clearly shown in the accom- 
panying diagrams, Figs. 46 — 48, showing the one-cell plant 
as supplied to the Moss Side Urban District Council, and 
Figs. 49 — 51 the general arrangement of sixteen-cell plant. 
The cell, which may be rectangular or circular in cross- 
section, is built up of cast-iron plates (see Fig. 45), and 
lined with firebrick, the top being closed in and provided 
with a hopper and bell opening for charging purposes. 
At the bottom the cell is open, and supported on two 
sides across a water trough, which covers the whole area 
of the base, the level in the trough being maintained 
at such a height as to effectually seal the interior of the 
cell from the outer atmosphere. Running transversely 
across the water trough is a cast-iron chamber fitted at the 
top with two inclined grates above the water level, which 
form a ridge running from side to side of the cell. 

The air required for combustion is supplied by means 
of a steam-jet blower fixed at one side of the cell, the air 
being blown into the cast-iron box described, and escaping 
through the two sloping grates into the mass of burning 
refuse situated above the water level. 

The quantity of air admitted through the blower is 
limited to that required to maintain a low temperature of 
combustion of the refuse, and distil off, or convert into a 
gaseous state, all the carbonaceous or organic matter with 
which it is charged. These gases are then led through an 
opening near the top of the cell into a separate chamber, 
where they mingle with a secondary supply of air, by the 
aid of which their ignition and complete combustion is 
secured at a temperature of about 1,800 deg. Fah. The 
combustion chamber, it will be observed, is surrounded 
with an annular chamber or jacket. Through this the 
secondary air supply is drawn and becomes considerably 
heated before it reaches the gases, thus adding materially 
to the efficiency and temperature of the combustion 
chamber. 



mason's refuse gasifier. 65 

The working of the cell is a continuous operation, 
and not interfered with by cleaning operations, the refuse 
being fed at intervals from the platform at the top, and 
the clinker and ashes drawn out of the water trough at 
the bottom as occasion requires. The process of gasifica- 
tion is not in any way interrupted either by the charging 
of the refuse fuel at the top or the withdrawing of the 
ashes and clinker at the bottom. No additional fuel of any 
kind is required except that for lighting the cell in the 
first instance. At the week ends the cells can be banked 
up with refuse and started again on Monday morning by 
merely opening the blower. The regulation of the air to 
the combustion chamber can be adjusted so as to meet 
various grades and qualities of refuse which may have to 
be dealt with, and in this way the highest efficiency of 
combustion is. secured. 

In the illustrations, Figs. 46 — 48, the gases are shown as 
being discharged direct from the combustion chamber to 
the chimney, but they can obviously be utilised when 
desired for steam-raising purposes (see Figs. 49 — 51), as the 
temperature of the gases escaping from the combustion 
chamber is, as stated, about 1,800 deg. Fah., and with 
average town's refuse an evaporative duty of about 1 lb. 
of water can be obtained for each pound of fuel. 

The cell illustrated in Figs. 46 — 48 measures 6 ft. 3 in. 
by 5 ft. in cross-section, giving a burning area of 31 sq. ft. 
as nearly as may be, while the grate surface measures 
14 J sq. ft.* The burning fuel in the cell is generally 
maintained at a thickness of about 4 ft. above the grate, 
and the air required for gasification is easily supplied by 
means of a J in. jet blower Avorking at about 40 lb. on the 
square inch. With such a cell it is found that 6 tons of 
refuse can be dealt with in the course of 24 hours with 
perfect ease, this refuse being reduced to about 25 per 
cent of its original weight, in which state it is drawn as 
ashes or clinker from the bottom of the cell of a character 
suitable either for grinding up into mortar or using as 
ballast for footpaths or roads. 



* This cell is rather less than the standard size, which affords a 
grate area of 24 sq. ft., and a burning area of 49 sq. ft. 

E 



66 



MASON S EEFUSE GASIFIER. 




Fig. 44. — View Showing Interior Construction of Mason's 
Single Cell Refuse Gasifier. 



MASONS REFUSE GASIFIER. 



67 




Fig. 45 — Perspective View Showing Exterior of Mason's 
Refuse Gasifer. 



68 



MASONS EEFUSE GASIFIEE. 




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72 



MASON'S REFUSE GASIFIEE. 



The following particulars of a test recently made with 
one of Mason's gasifiers at the yard of the Moss Side Urban 
District Council, under the supervision of Mr. D. Ainley, 
the sivperintendent of the cleansing department : Mr. 
George Darley, superintendent of the cleansing depart- 
ment. Leeds : W. Lawrence Gadd, F.I.C.. etc.: and William 
H. Fowler. Wh. Sc, Assoc. M. Inst. C.E., M.I. Meek E., etc.. 
will serve to illustrate the efficiency of the apparatus for 
the purpose of refuse destruction. The refuse dealt with, 
it may be remarked, was of a heavy, damp character, con- 
taining 30 - 3 per cent of moisture, and was not screened or 
assorted in any way. 

TEST MADE WITH A MASON'S REFUSE GASIFIER 

For the Destruction of Town's Refuse at the Yard of the 

MOSS SIDE URBAX DISTRICT COUNCIL 

Under the Supervision of 

Mr. D. Aiglet. .Superintendent of the Cleansing Department ; 

Mr. George Darley. Superintendent of the Cleansing Department, Leeds ; 

W. Lawrence Gadd, F.I.C., &c, 

and 

William H. Fowler, Wh. Sc, Assoc. M. Inst. C.E., M.I. Mech. E., &c. 

Date of Test, August 21st and 22nd, 1899. 





24 hours. 


Sectional Area of Cell 


6 ft. 3 in. x 5 ft. = 31 '25 sq. ft. 

16 sq. ft. 

Unscreened Ashpit Refuse 

30'3 per cent. 

13,552 lb. 


Area of Grate 






Total Weight of Fuel Burned 




565 lb. 


Weight per 3quare foot of Grate per hour 


35-25 lb. 


Pressure in Boiler supplying Steam to Jet Blower 
Weight of Steam used for Jet Blower per hour . . . 
Pressure of Forced Draught under Grate 


601b. 

110 lb. 

2£ in. water column. 

25 per cent. 

None. 


Percentage of Piesidue (clinker and a3h wet) 

Smoke from Chimney 



mason's refuse gasifier. 73 

In the course of the test observations were made of the 
temperature in the gasifier cell, and also in the combustion 
chamber. The readings of a Bailey's pyrometer indicated 
a temperature of 750 deg. Fah. in the cell, and a Siemens 
pyrometer of 1,625 deg. Fah. in the combustion chamber. 
This latter reading, however, was probably under the 
mark, since silver readily fused in the combustion 
chamber, showing that the temperature must have been 
over 1,733 deg. Fah. (the melting point of silver). 

During the course of the test samples of gas were drawn 
from the gasifier and also from the base of the chimney. 
Analyses of these showed their composition to be as 
follows : — 

Analysis of Gases from Gasifier. 

Per cent. 

Carbon-dioxide (C 2 ) 130 

Carbon-monoxide (C 0) lO'O 

Oxygen 2*4 

Hydrocarbons (C 2 H 4 ) 1*6 

Hydrogen 13*6 

Nitrogen 59'2 



99-8 
Gases from Base of Chimney. 

(Average of three analyses.) Per cent. 

Carbon-dioxide (C 2 ) 11'5 

Carbon-monoxide (C 0) 1'9 

Oxygen 4*6 

Hydrocarbons (C 2 H 4 ) 1*3 

Hydrogen 2*0 

Nitrogen 787 



100-0 

The steam required for the jet blowers was supplied by 
a small independent boiler, and the heat evolved by the 
combustion of the gases distilled from the refuse in this 
test was permitted to escape freely into the atmosphere 
from a chimney only 25 ft. in height, and it is of interest 
here to remark that although this gasifier has been in 
operation for more than 18 months, and is surrounded by 
good residential property within a radius of 50 yards of 
the site, not a single complaint has been made by any 
resident. As already stated, the heat from the gasifier, 
which gave a flame 19 ft. in length, can, if desired, be 
utilised for raising steam or other useful purpose. 



74 HOESFALL KEFUSE DESTEUCTOE. 

The Horsfall Refuse Destructor. — A longitudinal 
section of this destructor is shown in Fig. 52, and a 
sectional plan in Fig. 53. It consists of a series of grates 
arranged side by side, and in the larger destructors two 
sets of these grates placed end to end, as in the figures. 

The refuse to be destroyed is tipped on to the platform 
at the top of the structure, from which it is shoveled into 
the feed holes by hand. Immediately below the feed hole 
is the top of the main flue, on to which the garbage is first 
fed. The heat from the flue gases maintains the flue 
structure at a considerable temperature, and hence the 
green refuse tipped on its upper surface must be dried 
to a certain extent, and perhaps raised in temperature. 

On either side of the " table " is a sloping hearth 
down which the refuse gravitates until it reaches the back 
end of the grate. The hearth also forms part of the flue 
structure, and hence the refuse is dried and heated all the 
way from the feed hole to the grate upon which it is 
burnt. 

The products of combustion pass away from the burn- 
ing refuse into the exhaust flues immediately over it, and 
from thence along the cross flues, Fig. 55, to the downcast 
apertures through which they pass to the main flue 
beneath. These cross flues also assist in maintaining the 
whole upper structure at a higher temperature than the 
atmosphere, to assist in drying and heating the refuse. 

Running by the side of the main flue are a couple of 
smaller flues which convey air from the blast apparatus to 
the grates. 

In Fig. 53 will be seen a number of rectangular boxes on 
each side of the grates. These are cast-iron ducts through 
which the air-blast passes on its way from the blast flues to 
the ashpits. The chief use of these ducts is not so much 
to warm the blast, although that is desirable, but to main- 
tain the sides of the grate intact. The constant clinkering 
eventually wore away the brick sides of the grate and 
undermined the walls, until the cast-iron boxes were put 
in. 

The incandescent condition of the firebrick lining of 
the furnace tends to produce a very high temperature in 
the furnace and consequently the fumes given off from the 
burning refuse are completely cremated before reaching 
the chimnev stack. 



HOKSFALL REFUSE DESTRUCTOR. 



75 




Fig. 52. — Longitudinal Section ; Horsfall Destructor. 




Fig. 53 Plan at Grate Bar Level ; Horsfall Destructor. 



76 



HORSFALL REFUSE DESTRUCTOR. 




z- i£U -§ :£ti L! 

Fig. 54. — Front View ; Horsfall Destructor. 



tP>. 




&— — 42 



Fig. 55.— Plan at Level of Cross Flues ; Horsfall Destructor. 



HORSFALL REFUSE DESTRUCTOR. 



77 




Fig. 56.— Plan at Ashpit Level ; Horsfall Destructor. 




Fig. 57. — Plan Showing Air Passages ; Horsfall Destructor. 



78 HORSFALL REFUSE DESTRUCTOR. 

Fig. 54 shows a front view of the furnace with cleaning 
and clinkering doors. 

A sectional plan of the furnace at the level of the ash- 
pit is shown in Fig. 56, and another, showing the air passages 
leading to the blast apparatus, in Fig. 57. These air passages 
can also be seen in Fig. 52 in the tipping platform, and the 
air, which passes through them to the fire, picks up some 
of the heat which otherwise would be radiated and lost. 

It is found that a blast pressure of not more than 1 in. 
of water is quite sufficient for all purposes ; in fact, superior 
results have been obtained with this over higher pressures. 
It is also noteworthy that the chimneys attached to these 
destructors are free from smoke, showing that the 
carbonaceous matter has been completely consumed. 

In places where the refuse contains much matter, which 
is likely to escape from the chimney as dust, a collecting 
chamber is interposed between the destructor and the 
chimney, and this is found to completely get rid of any 
nuisance in this direction. The amount of dust is con- 
siderable. At Edinburgh the amount collected was about 
50 cubic feet per week. Its density is about 30 lb. per cubic 
foot, and it closely resembles finely ground reddish fire-brick. 

At Bradford the density is nearly double that at 
Edinburgh, the original refuse containing about 40 per cent 
of nightsoil and 5 per cent of vegetable refuse. 

At Oldham the waste heat is used to generate steam 
for mechanical purposes, and to assist in supplying steam 
to the electric lighting station. 

The following table of flue-gas analysis is reproduced 
from Professor Barr's report on the Oldham destructor : — 

Samples. A B C D E 



Carbonic acid ' 8'6 15*5 181 8'5 13'3 

Oxygen 10'9 3 '9 1*4 107 6-3 

Nitrogen - j 80'5 80*6 ; 80'5 80'8 80*4 

Excess of air per cent 113 23 7 70 43 

No hydro-carbons or carbonic oxide were found in the 
gases, and the average temperature was about 1,600 deg 
Fah. The samples A, B, and C were taken from a four-cell 
furnace, while J) and E were taken from a six-cell furnace. 



HORSFALL REFUSE DESTRUCTOR. 



79 



In the following tables the results are given of some 
trials carried out by Professor Barr and Lord Kelvin : — 



X X X 

2 So C A 

°2 O C^"<0 CO !M 50 

t-- c- cm 



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HOBSFALL EEFUSE DESTEUCTOB. 



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WARNER PERFECTUS REFUSE DESTRUCTOR. 



81 



Warner Perfectus Refuse Destructor. — The accom- 
panying illustrations, Figs. 58 and 59, show the latest type 
of destructor constructed by Messrs. Goddard, Massey, and 
Warner. The drawings in question are illustrations of the 
destructor as erected at Torquay, Fig. 58 being a section 
through one of the four cells, and Fig. 59 a section of one 







Fig. 58. — Section through one of the four Cells. 

of the two boilers. The installation comprising four cells 
back to back, have each about 26 superficial feet of fire- 
bars, of the rocking type, upon the wedge-shape principle. 
At the back of the firebars directly under the hoppers is a 
firebrick drying hearth with a reverberatory arch built 



82 



WARNER PERFECTUS REFUSE DESTRUCTOR. 



over so as to radiate heat upon the newly-fed refuse 
upon the hearth, thus partially drying it before it reaches 
the fire. Two multitubular boilers are built in between 
the cells, the shells of which are 3 ft. diameter by 12 ft. 
3 in. long, with steam drum 3 ft. diameter by 9 ft. long, 
and each is set at a working pressure of 80 lb., but tested 




Fig. 59. — Section through one of the two Boilers. 

up to 140 lb. upon the square inch. There are two engines, 
one horizontal, having a steam cylinder 10 in. by 20 in. 
stroke, and one vertical engine with steam cylinder 6 in. 
diameter. 

The horizontal engine is used for driving a heavy mortar 
mill, having a pan 7 ft. diameter, and a Warner's clinker 



WARNER PERFECTUS REFUSE DESTRUCTOR. 83 

mill, also for driving a dynamo for producing electricity 
for lighting the works and the district in the immediate 
vicinity of the destructor. The vertical engine is used for 
driving the high-pressure fan, air from which is drawn 
through an 18 in. iron pipe from over the top of the 
tipping platform, so that the foul air from the refuse may 
be extracted from the main building and passed under the 
firebars. 

An oil-jet cremator has been provided in the main 
flue, but this has not yet been made use of, as the tempera- 
ture in the cells has been found sufficient to consume 
without nuisance all the refuse delivered to the destructor. 

The circular chimney shaft, constructed of red brick and 
surmounted by a cast-iron cap, rises to a height of 150 ft. 
above the ground line, and rests upon a solid bed of 
concrete 25 ft. 6 in. square, 12 ft. thick, carried down to a 
depth of 19 ft. below the ground level. In addition to 
being used in connection with the destructor, a 15 in. pipe 
from the main line sewer in the immediate vicinity has 
been brough to and connected to the cremator chamber. 
The shaft thus acts as a sewer ventilating column. The 
shaft is lined with firebrick to a height of 50 ft. At the 
base of the shaft is constructed a special dust-catching 
chamber, which prevents the possibility of any dust being 
carried out at the top of the shaft. 

The following test of the Torquay destructor, was made 
on the 21st December, 1898, and quite independently of 
the manufacturers. 

Number and type of furnaces Four «' Warner Perfectus." 

Number of boilers and position Two, between the furnaces. 

Nature of refuse burned Unscreened ashpit refuse, very 

dry and containiDg a large 
quantity of waste paper, straw 
and packing paper. The first 
four loads delivered, being very 
light, were absolutely destroyed 
in the first hour and a quarter 

State of weather Very fine and dry. 

Duration of test 12 hours, 8-30 a.m. to 8-30 p.m. 

Number of men engaged Three in addition to half time 

of contractor's representative 
superintending running of the 
machinery. 

Wages of above 12s. 8d., including above. 

Total weight of refuse delivered to 
destructor during the day 



19 tons 7 cwt. 



84 



WARNER PERFECTUS REFUSE DESTRUCTOR. 



Total weight of refuse burned dur- 
ing the 24 hours 

Cost of burning per ton 

Colour of smoke from chimney 



Total quantity of water evaporated.' 
Starting at 8 a.m. from a cold- 
water feed and steam gauge 
standing at 00 

Refuse burned per pound of water' 
evaporated under disadvantageous 
conditions above referred to 

Average steam-pressure maintained ' 
during 12 hours in each boiler 
^31 readings) 

Highest reading, 11-30 a.m 

Lowest reading, 8 p.m 

Total I.H.P. per hour continuously 
at 201b. of water per I.H.P 

Residuals from total quantity of 
refuse delivered and burned, in- 
cluding that left on completion of 
test 



16 tons 7 cwt. = 36,624 lb. 

9-29d. 

First observation, 9-30 a.m., light 
brown ; 2-20 p.m., almost colour- 
less ; and at 4 p.m., light brown. 

-1,224 gallons = 12,240 lb. 



•2-99 lb. 



57 lb. 

105 lb. 
38 lb. 

51 indicated horse power. 

Tens cwt. qrs 

Clinker 54 

Fine ash 16 2 

Old tins and the like ..023 



Total 3 13 1 



Percentage of residuals 18-93 

The residuum from the destructor has been analysed by 
Dr. Bernard Dyer, of London, with the following result : — 



Moisture, organic matter, and water of combination 

* Phosphoric acid 

Lime 

Oxide of iron and alumina 

Carbonic acid, &c 

Silicious matter 

Nitrogen practically none 

* Equal to ammonia 

Equal to tribasic phosphate of lime 



Ground 
Clinker. 



Flue Dust. 



1-00 

1-06 

10-47 

33-54 

4-41 

49-52 



100-00 



2-31 



6-52 

0-96 

8-40 

33-34 

10-38 

40-40 



100-00 

017 
0-21 
2-09 



The information relating to the Warner Perfectus 
Destructor has been abstracted from a paper read by Mr. 
Henry A. Garrett, before the Institution of Mechanical 
Engineers. 



CONSTANTS FOR COMBUSTION. 



85 



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INDEX 



PAGE 

Air, Atmospheric, Composition of 7 

Air required for Combustion , 8 

Alternate Method of Firing 13 

Analysis of Chimney Gases 9 

Analysis of Coals 6 

Analysis of Gases from Horsf all Refuse Destructor 78 

Analysis of Gases from Mason's Refuse Gasifier 73, 78 

Anthracite Coal 6 

Bennis' Sprinkling Stoker 36 

Bituminous Coals 5 

Cannel Coal 5 

Cass Coking Stoker 43 

Chimney Gases, Instrument for Measuring Carbon Dioxide in 9 

Clench and Company's "Murphy'' Furnace 23 

Coal, Analysis of 6 

Coal, B.T.U. Evolved from the Constituents of lib. of 7 

Coal Gas. Methods of Burning 12 

Coal, Quality of, for Mechanical Stokers and Forced-draught 

Furnaces 16 

Coal, Varieties of 5 

Coking Coal 6 

Coking Method of Firing 13 

Coking Stoker, Proctor's 21 

Coking Stoker, The Cass 43 

Combustion, Air required for 8 

Combustion, Constants relating to 85 

Combustion, Phenomenon of 6 

Density of Constituents of Furnace Gases 9 

Density of Smoke, Estimation of 46 



INDEX. 87 

PAGE 

Destructors, Refuse, Types of 55—84 

Duff patent Forced-draught Furnace 18 

Duff patent Refuse Gasifier 64 

Economiser, The 9 

Firing, Alternate Method of 13 

Firing, Coking Method of 13 

Firing, Spreading System of 13 

Forced-draught Furnaces 14 — 21 

Fuel, Smokeless Combustion of 45 

Fuels, Classes of Coal 6 

Furnace Coal 6 

Furnace Gases, Constituents of , 9 

Furnace Gases, Measurement of 9 

Furnace, Mason's Forced-draught 18 

Furnace, Meldrum's Forced-draught 14 

Furnace, The "Murphy" 23 

Gas Coal 

Gasifier, Mason's Refuse 64 

Heat Evolved from the Constituents of Coal 7 

Horsfall's Refuse Destructor 74 

Lignite 5 

Mason's Forced-draught Furnace 18 

Mason's Refuse Gasifier 64 

Mechanical Stokers, Chief Features of 14 

Mechanical Stokers, Types of 21 — 44 

Meldrum's Forced -draught Furnace 14 

Meldrum's Koker Stoker 30 

Meldrum's Refuse Destructor 55 

' ■ Murphy " Furnace 23 

Paris Smoke Commission Trials 48 

Proctor's Coking Stoker 21 

Proctor's Shovel or Sprinkling Stoker 33 



88 INDEX. 

PAGE 

Ransome and Rapier's Sprinkling Stoker 40 

Refuse Destructors 55 — 84 

Refuse, Rate of Destruction per sq. ft. of grate 58, 61, 72, 79, 84 

Ringlemann Smoke Test 47 

Smoke Commission Trials, Paris 48 

Smoke, Estimation of the Density of 46 

Smoke, The Prevention of 45 

Spreading System of Firing : 13 

Sprinkling or Shovel Stoker, Proctor's , 33 

Sprinkling Stoker, Bennis' 36 

Sprinkling Stoker, Ransome and Rapier's 40 

Stoker, Bennis' Sprinkling 36 

Stoker, Meldrum's Koker 30 

Stoker, Proctor's Coking 21 

Stoker, Proctor's Shovel or Sprinkling 33 

Stoker, Ransome and Rapier's Sprinkling 40 

Stoker, The Cass Coking 43 

Stokers, Mechanical, Chief Features of 14 

Stokers, Mechanical, Types of 21 — 44 

Table of Constants relating to Combustion 85 

Test of Bennis' Sprinkling Stoker 40 

Test of Horsf all's Refuse Destructor 79 

Test of Mason's Refuse Gasifier 72 

Test of Meldrum's Koker Stoker 32 

Test of Meldrum's Refuse Destructor 61—63 

Test of " Murphy" Furnace 29 

Test of Warner Perfectus Refuse Destructor 83 

Test, Ringlemann Smoke 47 

Tests, Smoke Commission at Paris 53 

Warner Perfectus Refuse Destructor 83 



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5,000 FRANCS AWARDED TO THE 
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In COMPETITIVE TESTS made toy tne 
MUNICIPALITY of PARIS. 

The Delegates of the Technical Commission of the Municipality of Paris have con- 
cluded their tests with 1 lO different systems of stoking, representing 76 ia France, 19 
in England, 4 in Germany, 3 in America, 3 in Austria-Hungary, 2 in Italy, 1 in Belgium, 
1 in Poland, and 1 nationality unknown. 

The following are extracts from the report of the Committee in announcing their 
award :— 

In referring to No. 85 (Proctor's) Stoker test, they say:-" In the trials made at 
Javal Workshops, the Smoke Consumer has been NEARLY PERFECT, the 
density of the smoke being only 7£ per cent, compared with an ordinary fire. 
This is a very remarkable result. " 

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"The system appears very appropriate for a range of boilers" 

" One can find in its conditions safety in practical working. It appears to be 
what is required at tbe present time for its utility." 




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PRICE, 
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Niekel Cases. 

7s. 9d. 

Post Free in the 
United Kingdom. 

Anywhere Abroad, 

9s. 

Post free. 



Large Size, 2V dial, 

12s. 9d. 

Post free, U.K. 

Anywhere Abroad, 

XSs. 




An Aceurate and 

Reliable 

Instrument. 



It is only 

neeessary to turn 

two nuts; the 

instrument does 

the rest. 



Saves no end 

of 

time and worry. 



READ WHAT USERS SAY. 
Professor JOHN" GOODMAN, Yorkshire Cot-lege, Assoc.M.Inst.C.E., M.LMech.E., says:— 
"' 1 like the Calculators very much. I consider them a marvel of cheapness, and I 
hope you will get a very big sale for them." 
WILFRED J. LINE HAM ," M.Inst.C.HL, M.LMech.E., Head of the Engineering Depart- 
ment of the Goldsmiths' Institute, remarks: — 

"The Mechanical Calculator is a decided boon to the draughtsman and the engineer- 
ing teacher. A child could understand it, and I have no doubt you will have a 
tremendous sale." 
Professor W. W. F. PULLEN, Assoc. M. Inst. C.E., M.LMech.E., South Western Poly- 
technic, says; — 

" I cannot speak too highly of the Pocket Calcu'ator. Its great advantage over a 
slide rule is that it can be carried in the pocket without inconvenience. The figures are 
always clean, while the accuracy obtained with it is equal to that with a 10-inch slide 
rule. In my opinion it is the most useful instrument an engineer can possess." 

SEND FOR DESCRIPTIVE CIRCULAR-FREE. 

The Scientific Publishing Co., 

53, New Bailey Street, MANCHESTER. 



NON-MAGNETIC 

Keyless Lever WATCHES 

W (C) For ENGINEERS, (j) V* 

PRICE, 

50/- 

Post Free, 

in 

Oxydised Case 




A 

VALUABLE 

COMPANION 

for 

Engineers 

making Tests. 



Chronograph Action. 
Records Seconds & Minutes. 
Strong & Thoroughly Reliable 



THE SCIENTIFIC PUBLISHING CO., 



83, New Bailey Street, 

MANCHESTER, England. 



